**6. Repair principles and techniques**

The ideal method of flexor tendon repair should allow a healing response precisely at the tendon ends but not between the tendon and its surroundings, creates a repair site with minimal bulk and low friction, and places enough force across the repair to promote motion and remodelling [14].

two-strand techniques. The choice of core suture can be made independent of the choice of epitendinous repair. There is little evidence to recommend one suture material over another. Steel and fibrewire have been shown to be stronger than nylon, Prolene and braided polyester,

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The surgeon must not only be aware of how to repair a lacerated flexor tendon but must also have an understanding of the postoperative rehabilitation regimen before consenting a patient for surgery. Failure to comply with rehabilitation may result in poor patient outcomes despite meticulous repair technique. Unfortunately, the best rehabilitation regimen remains to be elucidated. This is further convoluted by a paucity of well-designed randomised control trials with a Cochrane Collaboration analysis [37] being withdrawn in 2010 for being out of date and the most recent systematic review concluding that there is weak evidence supporting both early active motion protocols and combination protocols [38]. Therefore, it is imperative that the surgeon be aware of both current rehabilitation regimens as well as future directions. Current postoperative protocols for patients with flexor tendon injuries are immobilisation, early passive mobilisation and early active mobilisation [39] (**Figure 1**).

Immobilisation may seem counterintuitive considering the plethora of studies showing the benefits of early mobilisation on the repair strength, tenocyte healing and formation of adhesions [14, 40–44]. However, there are certain situations in which immobilisation is preferable.

• Are unable to adhere to early mobilisation protocols such as children and those with cognitive

• Have injuries to other structures that could potentially be damaged by early mobilisation

O'Connell et al. followed 78 children (under the age of 16) for 24 months and found no benefits in early mobilisation protocols in children when compared to immobilisation [45]. However, immobilisation for more than four weeks resulted in functional deterioration of the repaired tendon [45]. Kato et al. found it difficult to encourage early active motion protocols in children aged less than six and found immobilisation for three to four weeks did not increase the inci-

For the non-compliant adult patient, the protocol of Cifaldi, Collins and Schwarze may be used [39, 47]. It involves three to four weeks of immobilisation in a forearm-based dorsal splint or cast (20° wrist flexion, metacarpophalangeal (MP) joints in 50° flexion and the interphalangeal (IP) joints in full extension) followed by a weaning program (it may also be used in children) [47]. Weaning involves modifying the splint so that the wrist is in neutral and instructing the patient to remove the splint every hour and passively flexing

with no significant difference between the latter three [36].

**7.1. Immobilisation**

deficits.

These include patients who [39]:

such as fractures, nerves and vessels.

dence of tendon rupture or decrease function [46].

• Are unwilling to adhere to strict early mobilisation protocols.

**7. Postoperative rehabilitation following flexor tendon repair**

The characteristics of an ideal tendon repair were described by Strickland [31] and confirmed by a large body of research data [14]. These are:


Strength of the repair immediately post operatively is reliant on the suture and is therefore entirely responsible for the stability in early motion stress. Ideally, the suture material used should have high tensile strength, be inextensible, cause no tissue reaction and be easy to handle and knot [31]. Flexor tendon repairs consist of two parts. The core sutures and the epitendinous sutures.

Core sutures provide strength to the tendon repair. A 3/0 or 4/0 non-absorbable braided or monofilament suture are optimal for use as core suture [32]. The number of core sutures in the repair and the size of the suture is proportional to the strength of the repair. However, increasing the number of suture strands within the repair leads to increased bulk of the repair. Another factor in determining strength of the tendon repair is the grip of the core sutures. Increasing the grip of the core suture prevents the suture from pulling out of the tendon after repair [32].

The epitendinous sutures ensure smoothness of gliding and also increases the tensile strength of the repair. A locked running suture also reduces the rate of gap formation [32].

Large gaps in the tendon repair prevents healing with Gelberman et al. demonstrating that 3 mm is the maximum permissible gap to allow tendon healing [33].

Other factors include minimal handling to reduce adhesions and to avoid vascular interference to the repaired tendon [33]. Tendon lacerations less than 60% of the tendon diameter should not be repaired [34].

There are many techniques available for repairing the tendon and these have been described in detail elsewhere [35]. Four-strand techniques are generally recognised to be superior to two-strand techniques. The choice of core suture can be made independent of the choice of epitendinous repair. There is little evidence to recommend one suture material over another. Steel and fibrewire have been shown to be stronger than nylon, Prolene and braided polyester, with no significant difference between the latter three [36].
